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Biomedical subjects

B Stolze

Publications and source records attributed to B Stolze.

11 recordsLinked to original sources
PubMed1992

Tumorigenicity, mucin production and AM-3 epitope expression in clones selected from the HT-29 colon carcinoma cell line.

Two mucin-producing cell clones (16.2 and 12.2) and a mucin-deficient clone (15.2) were selected from the established human adenocarcinoma cell line HT-29 by limiting dilution and Alcian blue staining. The amounts of the mucin antigen detectable on the cell surface with the monoclonal antibody (MAb) AM-3 decreased in the order HT-29 greater than 16.2 greater than 12.2 greater than 15.2 = 0. The binding avidity of AM-3 antibody to cells as well as to mucin extracts from each cell line decreased in the same order, indicating that the epitope density on the cell-bound mucins was highest in HT-29 and lowest in 12.2 cells. The parental line and the mucin-producing cell clones 16.2 and 12.2 showed no contact inhibition and grew as aggregates, while the 15.2 cells were well spread and formed a regular monolayer. The mucin-producing cell lines injected into nude mice yielded solid tumors with different growth rates (HT-29 greater than 16.2 greater than 12.2), while the 15.2 cell clone was not tumorigenic at all. The relative amounts of total mucin-bound hexoses and of the mucin epitope AM-3 decreased in the xenografts in the order HT-29 greater than 16.2 greater than 12.2. The present system is suitable for investigating the role of mucins in growth of colon carcinoma cells and indicates that increased tumorigenicity in nude mice coincides with the increase in total mucin expression and the expression of the AM-3 mucin epitope in tumor tissue.

Adenocarcinoma↗
PubMed1991

Increased number of accessible sugar epitopes defined with monoclonal antibody AM-3 on colonic mucins is associated with malignant transformation of colonic mucosa.

Monoclonal antibody AM-3 detects a mucin sugar epitope (AM-3 epitope) the expression of which increases in the course of human colon carcinogenesis parallel to the gradual morphological alterations (so called adenoma-carcinoma sequence). In the present report the AM-3-positive mucin has been purified from human normal and carcinomatous colonic tissue. About 300-fold enrichment of the epitope per protein from both sources was achieved after ultracentrifugation, gel filtration on Sepharose CL-6B and isopyknic gradient centrifugation. Slot-blot and enzyme-linked immunosorbent assays of the purified preparation indicated not only different amounts of the mucins but also a consistent qualitative difference between the molecules from both sources. The qualitative difference could be obliterated by a partial removal of the AM-3 epitope from the tumor-derived mucin with neuraminidase. The visualization of the molecules by rotary shadowing indicated that the mucins from both sources have similar length distribution, 80% of the molecules being 100-600 nm long. The reaction with AM-3 antibody followed by rotary shadowing showed that in the purified preparations more than 95% of the tumor-derived molecules and 74% of the normal colon tissue-derived molecules carried the epitope. The tumor-derived mucins bound, on the average, 34 +/- 15 (SD) antibodies/1000 nm of the protein core while the mucin from normal colon tissue carried 12 +/- 11 antibodies/1000 nm of the protein core. These data indicate that the increased expression of AM-3 epitopes during malignant transformation of the human colon is due to accumulation of AM-3-positive mucin as well as a higher number of accessible AM-3 epitopes on this mucin.

Antibodies, Monoclonal↗
PubMed1990

In vitro assay to test differential substrate affinities of growing axons and migratory cells.

An in vitro assay is presented in which different soluble substrates are arranged in narrow alternating stripes which forces growing axons and migratory cells to choose between them. The usefulness of this assay is exemplified by offering goldfish retinal axons and glial cells of the optic nerve a variety of substrates in stripes. Given a choice between substrates of unequal growth supporting activities axons and migratory cells grow in stripes, thus expressing their preference for one of the substrates. Growth in stripes was observed 1. when a substrate with growth promoting properties was next to one which did not possess these properties, 2. when the growth promoting activity of a substrate applied to both stripes was in one stripe blocked by an antibody, 3. when two different growth promoting substrates were offered.

Animals↗
PubMed1990

Violet mink develop an acute disease after experimental infection with Aleutian disease virus (ADV) isolate ADV SL3.

Six-Aleutian (aa)-genotype violet mink were infected intraperitoneally with the Aleutian Disease Virus (ADV) bone marrow derived isolate ADV SL3. All animals developed virus-specific antibodies and hypergammaglobulinaemia. Mortality during the fourteen week duration of the infection was 50%. The virus induced (histo)pathological lesions typical for Aleutian Disease. By immunohistochemical examination using a virus capsid-specific monoclonal antibody viral antigen was detected in lymph nodes, spleen, kidneys and once in hepatic Kupffer cells. By Southern blot and in situ hybridization studies with strand-specific RNA probes able to distinguish viral replicative forms from merely sequestered genomic DNA, ADV replication was detected in mesenteric lymph nodes and spleen. In one mink DNA replicative forms were also found in bone marrow cells or mononuclear cells of the peripheral blood, respectively. Only single-stranded viral DNA was detected in liver, kidney, gut and lung of infected animals. From Southern blot hybridization results a different, possibly organ-specific permissiveness of ADV in vivo is suggested.

Acute Disease↗
PubMed1990

Antigen distribution in organs of mink with Aleutian disease parvovirus infection.

On tissues from naturally infected non-Aleutian mink an immunohistological study was performed using monoclonal antibodies and the immunoperoxidase method. Structural proteins of ADV were demonstrated in cryosections and in ethanol-fixed and paraffin-embedded material which provide antigen detection in a similar amount together with good histological structure. In lymphoid organs viral antigen was restricted to B-cell areas, particularly lymphoid follicles. The pattern of antigen distribution was typical for follicular dendritic cells which are capable to retain immune complexes. Beside macrophages in the interior of lymphoid follicles most likely proliferating B-lymphoblasts reveal nuclear and cytoplasmatic presence of structural proteins indicating viral replication. Cells of the mononuclear phagocyte system such as cells of lymphatic sinuses and hepatic Kupffer cells harbor viral protein in the cytoplasm, probably resulting from phagocytosis of immune complexes. Renal glomeruli were consistently negative for virus antigen whereas in interstitial infiltrates cells resembling macrophages stained positive for ADV structural proteins.

Aleutian Mink Disease↗
PubMed1990

Mechanisms contributing to the virus persistence in Aleutian disease.

In this review published results and further studies concerning the persistence of Aleutian disease virus (ADV) isolate SL3 are presented. By Southern blot and in situ hybridization with strand-specific RNA probes focal replication of ADV-DNA was demonstrated in spleen, mesenteric lymph nodes, sporadically in mononuclear cells of the peripheral blood and bone marrow cells. These findings further support the concept of the lymphotropism of ADV. All cell culture-adapted ADV strains appear to have a ts-defect. Our in vitro studies indicate that the ADV isolate G(orham) induced the synthesis of comparable amounts of viral replicative DNA and viral proteins VP1 and VP2 at the non-permissive temperature of 37 degrees C. However, the viral progeny DNA synthesis was about threefold less at 37 degrees C compared to the permissive temperature of 32 degrees C. These findings suggest that the reduced level of viral progeny DNA at 37 degrees C accounts for the reduced production of infectious ADV. Finally, we provided experimental evidence that the apparent lack of neutralizing antibodies in AD is due to the masking of critical viral epitopes by cellular phospholipids.

Aleutian Mink Disease↗
PubMed1989

Efficient medium for impingement and storage of enveloped viruses.

Airborne infections with pathogenic viruses play an important role in the transmission of diseases amongst men and animals. We compared several media intended for impingement of viruses from virus-contaminated air and for their preserving effect for two enveloped viruses. Sindbis (SINV) and vesicular stomatitis virus (VSV), members of the families Toga- and Rhabdoviridae, respectively, were chosen as indicator agents. Amongst the media tested, a sampling fluid consisting of phosphate buffered saline, pH 7.2, 0.5% bovine serum albumin, 0.5% gelatine (PBSplus) was most efficient to minimize the sampling stress during impingement and to preserve the infectivity SINV and VSV under stringent conditions at 37 degrees C. About 50% of virus infectivity was recovered 15.7 or 30 hours, respectively, after the beginning of storage. Thus the recommended medium is also suitable for shipment and storage of diagnostic virus samples.

Air Microbiology↗
PubMed1987

Apparent lack of neutralizing antibodies in Aleutian disease is due to masking of antigenic sites by phospholipids.

It is generally accepted that Aleutian disease virus (ADV) cannot be neutralized by antibodies either in vivo or in vitro. We found several ways to demonstrate neutralization of ADV by specific antibodies from mink. It was essential to make ADV monodisperse by treatment with sodium lauroyl sarkosyl or n-butanol or by filtration through 0.05-micron membranes before neutralization tests. In kinetic experiments, there was a 95% loss of virus infectivity within the first 5 min of reaction, but a resistant fraction of about 1% remained after 1.5 hr of incubation. Neutralization titers between 1:160 and 1:640 were found in sera from naturally and experimentally infected mink. A positive relation was consistently found between neutralization and ELISA titers. Furthermore, separation of phospholipids from ADV was shown by thin-layer chromatography of butanol-extracted virions. By reconstitution of monodispersed ADV with various lipids, phospholipids were found to interfere with virus neutralization by attachment to the virus surface.

Aleutian Mink Disease↗
PubMed1987

Recognition of position-specific properties of tectal cell membranes by retinal axons in vitro.

In order to test the preference of growing axons for membrane-associated positional specificity a new in vitro assay was developed. In this assay, membrane fragments of two different sources are arranged as a carpet of very narrow alternating strips. Axons growing on such striped carpets are simultaneously confronted with the two substrates at the stripe borders. If there is a preference of axons for one or the other substrate they become oriented by the stripes and grow within the lanes of the preferred substrate. Such preferential growth could, in principle, be due to affinity to attractive factors on the preferred stripes or avoidance of repulsive factors on the alternate stripes. This assay system was used to investigate growth of chick retinal axons on tectal membranes. Tissue strips cut from various areas of the retina were explanted and the extending axons were confronted with stripes of cell membranes from various areas within the optic tectum. Tectal cell membranes prove to be an excellent substrate for the growth of retinal axons. Nasal and temporal axons can grow well on membranes of both posterior and anterior tectal cells. If, however, temporal axons are given a choice and encounter the border between anterior and posterior membranes they show a marked preference for growth on membranes of the anterior tectum, their natural target area. Nasal axons do not show a preference in this assay system. The transition from nasal to temporal properties within the retina is abrupt. In contrast, the transition from anterior to posterior properties of the tectal cell membranes occurs as a smooth gradient. Significantly, the positional differences of tectal membrane properties are only seen during the period of development of the retinotectal projection and are independent of tectal innervation by retinal axons. These anterior-posterior differences disappear by embryonic day 14.

Animals↗
PubMed1986

Epitopic mapping of structural and nonstructural Aleutian disease virus proteins.

Common antigenic properties for p85 and p75 but a different antigenic character for p71 Aleutian disease virus (ADV) proteins were demonstrated by Western blot analysis with monoclonal antibodies. It was shown that four hybridomas (ADV-Hy 47, 66, 77 and 84) with specific reactivity for structural proteins p85 and p75 also recognized p25 but not the p71, nonstructural, protein. In turn, the monoclonal antibody ADV-Hy 2 recognized the p71 protein only. For further studies of their antigenic properties, the ADV proteins were subjected to enzymatic or chemical cleavage. The derived peptide fragments were analyzed by epitopic mapping. Depending on the cleavage reagent and monoclonal antibody applied, specific peptide maps were revealed. The maps of p85 and p75 were very similar, indicating that both proteins shared an extensive antigenic relationship. After cleavage with alpha-chymotrypsin and N-chlorosuccinimide and by using the ADV-Hy 84 monoclonal antibody, unique peptide fragments were identified with p85 which had no counterparts in p75 fragments.

Aleutian Mink Disease Virus↗